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Abstract:

Disclosed is a liquid treatment apparatus for processing a lower surface
of the substrate. The apparatus includes a first nozzle disposed below a
lower surface of the substrate retained by the substrate retaining unit
to eject a treatment liquid towards the lower surface of the substrate,
the first nozzle having a plurality of first ejection ports, which are
arrayed from a position opposing a central portion of the substrate
retained by the substrate retaining unit to a position opposing a
peripheral portion of the substrate retained by the substrate retaining
unit. An ejecting direction of the treatment liquid ejected from the
first ejection port is inclined towards a rotation direction of the
substrate rotated by the rotational driving unit.

Claims:

1. A liquid treatment apparatus comprising: a substrate retaining unit
comprising a retaining member configured, to hold a peripheral edge of a
substrate to retain the substrate horizontally; a rotational driving unit
configured to rotate the substrate retaining unit; a first nozzle
disposed below a lower surface of the substrate retained by the substrate
retaining unit to eject a treatment liquid towards the lower surface of
the substrate, the first nozzle comprising a plurality of first ejection
ports, which are arrayed from a position opposing a central portion of
the substrate retained by the substrate retaining unit to a position
opposing a peripheral portion of the substrate retained by the substrate
retaining unit; and a liquid supply mechanism that supplies a treatment
liquid to the first ejection ports, wherein each of the first ejection
ports is configured to eject the treatment liquid towards the lower
surface of the substrate in an ejecting direction which is inclined
towards a rotation direction of the substrate rotated by the rotational
driving unit.

2. The liquid treatment apparatus according to claim 1, wherein: the
first ejection ports are arrayed along a straight line extending from the
position opposing the central portion of the substrate retained by the
substrate retaining unit to the position opposing the peripheral portion
of the substrate retained by the substrate retaining unit, and the
straight line extends in a radial direction of the substrate held by the
substrate retaining unit or extends parallel to the radial direction.

3. The liquid treatment apparatus according to claim 1, wherein: the
first nozzle comprises a bar-shaped portion extending in a radial
direction of the substrate retained by the substrate retaining unit, and
the first ejection ports are provided in the bar-shaped portion.

4. The liquid treatment apparatus according to claim 1, wherein: the
first nozzle comprises at least one second ejection port provided in an
area radially inside an area in which the first ejection ports are
provided, and the second ejection port is configured to eject a treatment
liquid vertically upward.

5. The liquid treatment apparatus according to claim 1, wherein: at least
radially outermost one of the plurality of the first ejection ports is
configured to eject a treatment liquid in an ejecting direction having a
radially outward component.

6. The liquid treatment apparatus according to claim 1, wherein: assuming
that an area covered by a treatment liquid at a moment when the treatment
liquid ejected from an ejection port of the first nozzle reaches the
lower surface of the substrate retained by the substrate retaining unit
is referred to as a "spot", the first ejection ports are configured to
form spots adjacent two of which overlap with each other.

7. The liquid treatment apparatus according to claim 1, wherein: the
first nozzle comprises at least one second ejection port provided in an
area radially inside an area in which the first ejection ports are
provided, and the second ejection port is configured to discharge a
treatment liquid vertically upward; and assuming that an area covered by
a treatment liquid at a moment when the treatment liquid discharged from
an ejection port of the first nozzle reaches the lower surface of the
substrate retained by the substrate retaining unit is referred to as a
"spot", an radially innermost one of the plurality of first ejection
ports is configured to form a spot which overlaps with a spot formed by a
treatment liquid ejected from the second ejection port.

8. The liquid treatment apparatus according to claim 1, further
comprising a second, nozzle configured to supply a treatment liquid onto
an upper surface of the substrate retained by the substrate retaining
unit.

9. The liquid treatment apparatus according to claim 1, wherein: the
liquid supply mechanism comprises a variable throttle, and wherein said
liquid treatment apparatus further comprises a controller configured to
vary an opening of the variable throttle according to a predetermined
sequence, when the treatment liquid is being supplied from the first
ejection ports onto the lower surface of the substrate.

10. The liquid treatment apparatus according to claim 1, wherein: the
first nozzle comprises a bar-shaped portion extending in a radial
direction of the substrate retained by the substrate retaining unit, and
a central portion located at a position opposing a central portion of the
substrate retained by the substrate retaining unit; the first ejection
ports are provided in the bar-shaped portion; the central portion
comprises at least one second ejection port configured to eject a
treatment liquid vertically upward; a through-hole is formed in the
central portion of the substrate retaining unit, and a treatment liquid
supply pipe penetrates through the through-hole; a cover is provided at
the central portion of the first nozzle to prevent a treatment liquid
once ejected towards the substrate from flowing into the through-hole;
the first ejection ports and the at least one second ejection port are
arrayed on a straight line, in a plan view.

11. The liquid treatment apparatus according to claim 1, wherein: the
first nozzle comprises a bar-shaped portion extending in a radial
direction of the substrate retained by the substrate retaining unit, and
a central portion located at a position opposing a central portion of the
substrate retained by the substrate retaining unit; the first ejection
ports are provided in the bar-shaped portion; the central portion
comprises at least one second ejection port configured to eject a
treatment liquid vertically upward; a through-hole is formed in the
central portion of the substrate retaining unit, and a treatment liquid
supply pipe penetrates through the through-hole; a cover is provided at
the central portion of the first nozzle to prevent a treatment liquid
once ejected towards the substrate from flowing into the through-hole;
assuming that an area covered by a treatment liquid at a moment when the
treatment liquid ejected from an ejection port of the first nozzle
reaches the lower surface of the substrate retained by the substrate
retaining unit is referred to as a "spot", the first ejection ports and
the at least one second ejection port are configured to form spots
arrayed along a straight line, in a plan view.

12. The liquid treatment apparatus according to claim 1, wherein: the
first nozzle comprises a bar-shaped portion extending in a radial
direction of the substrate retained by the substrate retaining unit, and
a central portion located at a position opposing a central portion of the
substrate retained by the substrate retaining unit; the first ejection
ports are provided in the bar-shaped portion; the central portion
comprises at least one second ejection port configured to eject a
treatment liquid vertically upward; a through-hole is formed in the
central portion of the substrate retaining unit, and a treatment liquid
supply pipe penetrates through the through-hole; a cover is provided at
the central portion of the first nozzle to prevent a treatment liquid
once ejected towards the substrate from flowing into the through-hole;
assuming that an area covered by a treatment liquid at a moment when the
treatment liquid ejected from an ejection port of the first nozzle
reaches the lower surface of the substrate held by the substrate
retaining unit is referred to as a "spot", the first ejection ports and
the at least one second ejection port are configured to form spots
arranged on a polygonal line, in a plan view.

13. The liquid treatment apparatus according to claim 1, wherein: the
first ejection ports are arrayed along a straight line extending from the
position opposing the central portion of the substrate retained by the
substrate retaining unit to the position opposing the peripheral portion
of the substrate retained by the substrate retaining unit; said liquid
treatment apparatus further comprises; a horizontal moving mechanism
configured to move the first nozzle along the straight line along which
the first ejection ports are arrayed; and a controller configured to
control the horizontal moving mechanism to move the first nozzle
according to a predetermined sequence, when the first ejection ports
eject a treatment liquid towards the lower surface of the substrate.

14. The liquid treatment apparatus according to claim 13, wherein: at
least some of the plurality of first ejection ports are arrayed along the
straight line at regular intervals; and the controller is configured to
control the horizontal moving mechanism to move the first nozzle at a
distance less than the interval between adjacent two of said at least
some first ejection ports.

15. A liquid processing method comprising: retaining a substrate in a
horizontal posture; providing a first nozzle comprising a plurality of
first ejection ports below a lower surface of the substrate retained by
the substrate retaining unit such that the first ejection ports are
arrayed from a position opposing a central portion of the substrate to a
position opposing a peripheral portion of the substrate; rotating the
substrate; and ejecting a treatment liquid from the first ejection ports
toward a lower surface of the substrate in ejecting directions each
having a component in a rotation direction of the substrate.

Description:

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is based on and claims the benefit of priorities
from both Japanese Patent Application No. 2010-293775 filed on Dec. 28,
2010, and Japanese Patent Application No. 2011-240325 filed on Nov. 1,
2011, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

[0002] The present disclosure relates to a liquid treatment apparatus and
a liquid treatment method used to conduct liquid treatment such as
cleaning and etching for substrates by supplying a treatment liquid to a
lower surface of the substrate while spinning it.

BACKGROUND ART

[0003] There have been known conventional substrate cleaning apparatuses
that clean substrates such as semiconductor wafers (hereinafter, also
referred to simply as "wafer(s)") by supplying a cleaning liquid to a
substrate which is rotating and held in horizontal posture.

[0004] JP9-290197A describes a substrate processing apparatus that
includes a spin chuck for retaining a wafer in horizontal posture and
rotating the wafer; and a cleaning liquid supply pipe extending inside a
rotating shaft of the spin chuck and having an opening for ejecting
cleaning liquid towards the center of the lower surface of the wafer
retained by the spin chuck. The peripheral area of the wafer lower
surface may not be sufficiently cleaned if the cleaning liquid is ejected
towards the center of the lower surface of the wafer W.

[0005] JP2005-353739A describes a substrate processing apparatus that
includes a spin chuck for retaining the wafer in horizontal posture and
rotating the wafer; and a two-fluid nozzle for jetting a two-fluid spray
towards the upper surface of the wafer retained by the spin chuck. The
two-fluid spray is formed from a nitrogen gas and a treatment liquid such
as a chemical liquid and is jetted in a band-like form having a length
nearly equivalent to the radius of the wafer. JP2005-353739A suggests
that such a two-fluid nozzle may also be disposed below the lower surface
of the wafer to clean the lower surface. However, a specific
configuration of such an arrangement is not disclosed.

[0006] JP2008-130763A describes a substrate processing apparatus that
includes a spin chuck for retaining the wafer in horizontal posture and
rotating the wafer; a two-fluid nozzle for jetting a two fluid spray
towards the upper surface of the wafer retained by the spin chuck, the
two fluid spray being a mixture of a nitrogen gas and a treatment liquid
such as a chemical liquid and is jetted in a band-like form having a
length nearly equivalent to a diameter of the wafer; and another nozzle
for ejecting a treatment fluid such as deionized water (DIW) towards the
central portion of the upper surface of the wafer W. In the apparatus of
JP2008-130763A, when a two-fluid nozzle jets a two fluid-spray onto the
upper surface of a wafer W, the two-fluid nozzle scans the upper surface
of the wafer W which is not rotating. Cleaning of the lower surface of
the wafer W is not described in JP2008-130763A.

DISCLOSURE SUMMARY

[0007] The present disclosure provides a liquid treatment apparatus and a
liquid treatment method capable of treating the lower surface of a
substrate efficiently.

[0008] In one aspect, there is provided a liquid treatment apparatus,
which includes: a substrate retaining unit comprising a retaining member
configured to hold a peripheral edge of a substrate to retain the
substrate horizontally; a rotational driving unit configured to rotate
the substrate retaining unit; a first nozzle disposed below a lower
surface of the substrate retained by the substrate retaining unit to
eject a treatment liquid towards the lower surface of the substrate, the
first nozzle comprising a plurality of first ejection ports, which are
arrayed from a position opposing a central portion of the substrate
retained by the substrate retaining unit to a position opposing a
peripheral portion of the substrate retained by the substrate retaining
unit; and a liquid supply mechanism that supplies a treatment liquid to
the first ejection ports, wherein each of the first ejection ports is
configured to eject the treatment liquid towards the lower surface of the
substrate in an ejecting direction which is inclined towards a rotation
direction of the substrate rotated by the rotational driving unit.

[0009] In another aspect, there is provided a liquid treatment method,
which includes: retaining a substrate in a horizontal posture; providing
a first nozzle comprising a plurality of first ejection ports below a
lower surface of the substrate retained by the substrate retaining unit
such that the first ejection ports are arrayed from a position opposing a
central portion of the substrate to a position opposing a peripheral
portion of the substrate; rotating the substrate; and ejecting a
treatment liquid from the first ejection ports toward a lower surface of
the substrate in ejecting directions each having a component in a
rotation direction of the substrate.

[0010] In the foregoing aspects, due to the provision of the first
ejection ports which are arrayed from a position opposing a central
portion of the substrate to a position opposing a peripheral portion of
the substrate, a treatment liquid can be supplied to the lower surface of
the substrate with high uniformity. In addition, since the ejecting
direction of the treatment liquid ejected from the first ejection port
towards the lower surface of the substrate is inclined towards a rotation
direction of the substrate, bouncing (splash-back) of the treatment
liquid upon collision against the lower surface of the wafer W can be
suppressed, resulting in Improved efficiency of the treatment.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a top plan view of a liquid treatment system which
includes substrate cleaning apparatuses in one embodiment;

[0012] FIG. 2A is a vertical cross sectional view showing the
configuration of the substrate cleaning apparatus in a state where a lift
pin plate and a cleaning liquid supply pipe are located at their lowered
positions;

[0013]FIG. 2B is a vertical cross sectional view showing the
configuration of the substrate cleaning apparatus in a state where the
lift pin plate and the cleaning liquid supply pipe are located at their
raised positions;

[0014]FIG. 2C is a top plan view of the substrate cleaning apparatus in a
state where a wafer is retained by a substrate retaining member and fixed
retaining members as shown in FIG. 2A;

[0015]FIG. 3 is a perspective view showing the configuration of the lift
pin plate of the substrate cleaning apparatus shown in FIGS. 2A and 2B;

[0016]FIG. 4 is a perspective view showing the configuration of a
retaining plate of the substrate cleaning apparatus shown in FIGS. 2A and
2B;

[0017]FIG. 5 is an enlarged vertical cross sectional view showing the
configuration of a connecting member extending downward from the lift pin
plate and a hollow accommodation member extending downward from the
retaining plate and accommodating the connecting member in the substrate
cleaning apparatus shown in FIGS. 2A and 2B;

[0018] FIG. 6 is an enlarged vertical cross sectional view showing the
configuration of the substrate retaining member provided on the retaining
plate in the substrate cleaning apparatus shown in FIGS. 2A and 2B;

[0019] FIG. 7 is an enlarged vertical cross sectional view showing a state
where the lift pin plate has been moved downward from the state shown in
FIG. 6;

[0020]FIG. 8 is an enlarged vertical cross sectional view showing a state
where the lift pin plate has been moved further downward from the state
shown in FIG. 7;

[0021]FIG. 9 is a perspective view showing the configuration of a
treatment fluid supply pipe and bar-shaped nozzle in the substrate
cleaning apparatus shown in FIGS. 2A and 2B, and the configuration of a
lifting mechanism for vertically moving them;

[0022] FIG. 10 is for explanation of the configuration of the treatment
fluid supply pipe and the bar-shaped nozzle, wherein (a) is a top plan
view, (b) is a vertical cross sectional view taken along line Xb-Xb of
(a), and (c) is a vertical cross sectional view taken along line Xc-Xc of
(a);

[0023] FIG. 11 is for explanation of the status where only a liquid is
ejected from the bar-shaped nozzle, wherein (a) is a diagram showing
regions wetted with the liquid upon reaching the lower surface of the
wafer W, (b) shows a side view showing the manner of liquid ejection from
an ejecting port of a bar-shaped portion of the bar-shaped nozzle, and
(c) is a side view showing the manner of liquid injection from an
ejection port of a central portion of the bar-shaped nozzle;

[0024] FIG. 12 is a diagram for explanation of spots formed on the wafer
by the chemical liquid ejected from ejection ports of the bar-shaped
nozzle;

[0025] FIG. 13 is for explanation for the status where a two-fluid spray
is ejected from the bar shaped nozzle, wherein (a) is a vertical cross
sectional view of the bar-shaped portion of the bar-shaped nozzle, and
(b) is a vertical cross sectional view of the central portion of the
bar-shaped nozzle;

[0026] FIG. 14 shows diagrams showing variations of the manner in which a
liquid-ejecting passage and a gas-ejecting passage meet near the ejection
port of the bar-shaped portion of the bar-shaped nozzle;

[0027] FIG. 15 is a schematic diagram for explaining a possible
modification of the liquid treatment apparatus;

[0029] FIG. 17 shows schematic plan views illustrating an example of a way
of shifting the bar-shaped nozzle while ejecting a liquid from the
ejection ports; and

[0030] FIG. 18 shows a vertical cross sectional view and a schematic
diagram showing the configuration around the ejection port in a modified
bar-shaped nozzle.

DESCRIPTION OF EMBODIMENTS

[0031] An embodiment of a liquid treatment apparatus will be described
with reference to the accompanying drawings.

[0032] First, a liquid treatment system including a substrate cleaning
apparatus in one embodiment of a liquid treatment apparatus will be
described below with reference to FIG. 1. As shown in FIG. 1, the liquid
treatment system includes: mounting tables 101 each for mounting thereon
a carrier accommodating a semiconductor wafer W (i.e., substrate to be
processed) (hereinafter, simply referred to as "wafer W") which is
transported thereto from the outside of the system; a transport arm 102
for removing the wafer W from the carrier; a shelf unit 103 for placing
thereon the wafer W removed from the carrier by the transport arm 102;
and a transport arm 104 for receiving the wafer W from the shelf unit 103
and for transporting the wafer W to the substrate cleaning apparatus 10.
As shown in FIG. 1, a plurality of (twelve, in the embodiment of FIG. 1)
substrate cleaning apparatuses are installed in the liquid treatment
system.

[0033] Next, a schematic configuration of the substrate cleaning apparatus
10 is described below with reference to FIGS. 2A and 2B. The substrate
cleaning apparatus 1.0 includes: a retaining plate 30 retaining the wafer
W; a lift pin plate 20 provided above the retaining plate 30 and
including lift pins 22 to support thereon the wafer W from below; a
rotational driving unit 39 equipped with an electric motor or the like to
rotate the retaining plate 30; a treatment fluid supply pipe 40 routed
through a through-hole 30a formed centrally in the retaining plate 30 and
a through-hole 20a formed centrally in the lift pin plate 20; and a
bar-shaped nozzle 60 for ejecting treatment fluids supplied via the
treatment fluid supply pipe 40 towards the lower surface of the wafer W.
The lift pin plate 20 is configured to rotate with being interlocked with
the retaining plate 30.

[0034] The lift pin plate 20, the treatment fluid supply pipe 40, and the
bar-shaped nozzle 60 can be moved vertically relative to the retaining
plate 30. FIG. 2A shows a state where the lift pin plate 20, the
treatment fluid supply pipe 40, and the bar-shaped nozzle 60 are
positioned at their respective lowered positions. FIG. 2B shows a state
where the lift pin plate 20, the treatment fluid supply pipe 40, and the
bar-shaped nozzle 60 are positioned at their respective raised positions.
The lift pin plate 20, the treatment fluid supply pipe 40, and the
bar-shaped nozzle 60 can be moved up and down between the lowered
positions as shown in FIG. 2A and the raised positions as shown in FIG.
2B.

[0035] Next, constituent elements of the substrate cleaning apparatus are
described in detail below.

[0036] As shown in FIG. 3, the lift pin plate 20 has a disk-like shape
with the through-hole 20a formed in its central portion. An annular
protrusion 20b is provided around the through-hole 20a to prevent a
liquid on the lift pin plate 20 from entering the through-hole 20a. The
treatment fluid supply pipe 40 is routed through the through-hole 20a. A
plurality of (three or four) lift pins 22 are provided on the upper
surface of the lift pin plate 20. The lift pins 22 are arranged at equal
angular intervals on a circumference near the peripheral edge of the lift
pin plate 20. Three rod-like connecting members 24 extend downward from
the lower surface (i.e., the surface opposite to the surface provided
with the lift pins 22) of the lift pin plate 20. The connecting members
24 are arranged at equal angular intervals on a circumference near the
peripheral edge of the lift pin plate 20.

[0037] As shown in FIG. 4, the retaining plate 30 has a disk-like shape
with the through-hole 30a formed in its central portion. The treatment
fluid supply pipe 40 is routed through the through-hole 30a. A rotary cup
36 is attached to the retaining plate 30 via a connecting member 38 as
shown in FIG. 2A. When the lift pin plate 20, the treatment fluid supply
pipe 40, and the bar-shaped nozzle 60 are at their lowered positions, the
rotary cup 36 encircles the peripheral edge of the wafer W retained by
the retaining plate 30. As shown in FIGS. 2A and 2C, two fixed retaining
members 37 are attached to the rotary cup 36 to retain the wafer W. The
detailed function of the fixed retaining members 37 will be described
later. Instead of attaching the fixed retaining members 37 to the rotary
cup 36, they may be connected to the retaining plate 30, or may be
directly attached to the connecting member 38. If the fixed retaining
members 37 are attached directly to the connecting member 38, the fixed
retaining members 37 can be enhanced in strength against a force applied
from a horizontal direction.

[0038] A hollow rotating shaft 34 is attached to the central portion of
the lower surface of the retaining plate 30 (i.e., the surface opposite
to the surface equipped with the rotary cup 36) to extend downward
therefrom. The treatment fluid supply pipe 40 is accommodated in the
cavity of the hollow rotating shaft 34. The rotating shaft 34 is
supported by a bearing (not shown) and is rotated by the rotational
driving unit 39 comprising an electric motor and so on. The rotational
driving unit 39 rotates the rotating shaft 34, thus rotating the
retaining plate 30 as well.

[0039] As shown in FIG. 4, three through-holes 30b (connecting member
through-holes) are formed in the retaining plate 30. The connecting
members 24 coupled to the lift pin plate 20 are each inserted slidably in
the through-hole 30b. The connecting members 24 connect the retaining
plate 30 and the lift pin plate 20 for their integral rotation while
preventing relative rotation between them; the connecting members 24
permit relative vertical movement between the retaining plate 30 and the
lift pin plate 20. The through-holes 30b are arranged in the retaining
plate 30 at equal angular intervals on a circumference on the retaining
plate 30. In addition, on the lower surface of the retaining plate 30,
the through-holes 30b are provided with three accommodation members 32
having a cylindrical shape. The accommodation members 32 extend downward
from the lower surface of the retaining plate 30 and accommodate the
connecting members 24 extending downward from the lower surface of the
lift pin plate 20. The accommodation members 32 are arranged at equal
angular Intervals on a circumference near a peripheral area of the
retaining plate 30.

[0040] Referring to FIG. 5, a further detailed description will be made
for the connecting members 24 extending downward from the lower surface
of the lift pin plate 20, and the accommodation members 32 extending
downward from the lower surface of the retaining plate 30. As shown in
FIG. 5, the cylindrical accommodation member 32 has an inside diameter
slightly greater than an outside diameter of the connecting member 24.
The connecting member 24 can move in a longitudinal direction of the
accommodation member 32 (i.e., vertical direction in FIG. 5) in the
accommodation member 32. As shown in FIG. 2A, when the lift pin plate 20
is at its lowered position, the connecting member 24 is completely
received in the accommodation member 32. Meanwhile, as shown in FIG. 2B,
when the lift pin plate 20 is at its raised position, only a lower
portion of the connecting member 24 is received in the accommodation
member 32. The connecting member 24 passes through the through-hole 30b
in the retaining plate 30 and protrudes upward from the retaining plate
30.

[0041] As shown in FIG. 5, a spring 26 is installed in the cavity of the
accommodation member 32 in a compressed state. The lower end of the
spring 26 is connected to the bottom of the connecting member 24 while
its upper end is connected to the lower surface of the retaining plate 30
in the vicinity of the through-hole 30b. Thus, the spring 26 urges the
connecting member 24 downward. In other words, force of the spring 26 to
return from the compressed state to an original state exerts a downward
force upon the connecting member 24 (i.e., force to move downward from
the retaining plate 30).

[0042] As shown in FIGS. 2A and 2B, an outer cup 56 is provided outside
the rotary cup 36 to surround the retaining plate 30 and the rotary cup
36. In addition, a drainage tube 58 is connected to the outer cup 56.
During cleaning of a wafer W, used cleaning liquid scatters outward from
the wafer W due to its rotation. The scattered liquid will be received by
the outer cup 56 and is drained through the drainage tube 58.

[0043] As can be seen in FIG. 2A, a movable, substrate retaining member 31
for supporting the wafer W from the lateral side of the wafer W is
provided on the retaining plate 30. When the lift pin plate 20 is at its
lowered position as in FIG. 2A, the substrate retaining member 31
supports the wafer W from its lateral side. When the lift pin plate 20 is
at its raised position as shown in FIG. 2B, the substrate retaining
member 31 is separated away from the wafer W. The operation of the
substrate retaining member 31 will be described more specifically with
reference to FIG. 2C. During wafer cleaning, the wafer W is retained by
the substrate retaining member 31 and the two fixed retaining members
(i.e., non-movable, substrate-retaining members) 37. At this time, the
substrate retaining member 31 presses the wafer W against the two fixed
retaining members 37. That is, the substrate retaining member 31 applies
to the wafer W a leftward force to press the wafer W against the fixed
retaining members 37. In the illustrated embodiment, since the wafer W is
retained by two fixed retaining members 37 and only one movable
substrate-retaining member 31, the configuration for retaining the wafer
W can be more simplified as compared with a configuration employing a
plurality of movable substrate retaining members 31 with no fixed
retaining member 37.

[0044] Then, the configuration of the substrate retaining member 31 will
be detailed below referring to FIGS. 6 to 8.

[0045] FIG. 6 shows a state where the lift pin plate 20 is moving from its
raised position as in FIG. 2B to its lowered position as in FIG. 2A. FIG.
7 shows a state where the lift pin plate has moved more downward from the
state shown in FIG. 6. FIG. 8 shows a state where the lift pin plate 20
has moved further downward from the state of FIG. 7 to reach the lowered
position as shown in FIG. 2A.

[0046] As shown in FIGS. 6 to 8, the substrate retaining member 31 is
supported by the retaining plate 30 via an axle 31a. More specifically, a
bearing unit 33 is attached to the retaining plate 30, and an axle
receiving hole 33a of the bearing unit 33 receives the axle 31a. The axle
receiving hole 33a is an elongated hole extending in a horizontal
direction, and the substrate retaining member 31 can move horizontally
along the axle receiving hole 33a. The substrate retaining member 31 can
thus swing around the axle 31a accommodated within the axle receiving
hole 33a of the bearing unit 33.

[0047] A spring member 31d such as a torsion spring is wound around the
axle 31a of the substrate retaining member 31. The spring member 31d is
adapted to impart the substrate retaining member 31a force to rotate the
substrate retaining member 31 around the axle 31a in the clockwise
direction in FIGS. 6 to 8. Thus, when no force is applied to the
substrate retaining member 31, the substrate retaining member 31 inclines
with respect to the retaining plate 30, as shown in FIG. 2B. A substrate
retaining portion 31b (described later) of the substrate retaining member
31, provided to hold the wafer W from its lateral side, then moves away
from a central portion of the retaining plate 30.

[0048] The spring member 31d has a linear portion extending outward from
the axle 31a to an inner well 33b of the bearing unit 33. The linear
portion is engaged with the inner wall 33b, thereby pushing back the axle
31a towards the center of the retaining plate 30. The axle 31a is thus
constantly pushed towards the center (leftward in FIGS. 6 to 8) of the
retaining plate 30 by the linear portion of the spring member 31d. When
the movable substrate retaining member 31 and the fixed retaining members
37 are supporting a wafer W having a relatively small diameter, the axle
31e is positioned in the axle receiving hole 33a at a position nearer to
the center (left side) of the retaining plate 30, as shown in FIGS. 6 to
8. When the movable substrate-retaining member 31 and the fixed retaining
members 37 is supporting a wafer W having a relatively large diameter,
the axle 31a moves rightward along the axle receiving hole 33a from the
position shown in FIGS. 6 to 8, against the force applied by the linear
portion of the spring member 31d. The magnitude of the wafer diameter
(small/large diameter) here refers to a magnitude that falls within a
tolerance range.

[0049] The substrate retaining member 31 has, in addition to the substrate
retaining portion 31b that retains the wafer W from its lateral side, a
pressure receiving member 31c at the side opposite to the substrate
retaining portion 31b with respect to the axle 31a. The pressure
receiving member 31c is set between the lift pin plate 20 and the
retaining plate 30. When the lift pin plate 20 is at or near the lowered
position, the lower surface of the lift pin plate 20 pushes the
pressure-receiving member 31c downward as shown in FIGS. 6 to 8.

[0050] While the lift pin plate 20 moves from its raised position to its
lowered position, the lower surface of the lift pin plate 20 pushes the
pressure receiving member 31c downward. Then, the substrate retaining
member 31 rotates counterclockwise around the axle 31a (in a direction
shown by the arrows in FIGS. 6 to 8). This rotation of the substrate
retaining member 31 around the axle 31a renders the substrate retaining
portion 31b to approach the wafer W from its lateral side. The wafer W is
held from its lateral side by the substrate retaining member 31, as the
lift pin plate 20 reaches the lowered position as in FIG. 8. At this time
when the wafer W is held at its lateral side by the substrate retaining
member 31, the wafer W is separated from the tip of each lift pin 22 and
is held above the lift pins 22. Depending on the size of the wafer W, the
axle 31a may slide rightwards along the axle receiving hole 33a from the
position shown in FIGS. 6 to 8, against the force applied by the linear
portion of the spring member 31d. Therefore, the wafer W can be held from
its lateral side without deforming nor damaging it even if the substrate
retaining member 31 and the fixed retaining members 37 hold a relatively
large wafer W, because the substrate retaining member 31 can shift in the
horizontal direction.

[0051] By employing such substrate retaining member 31, the substrate
cleaning apparatus 10 do not need a special driving mechanism (motive
energy source) for driving a substrate retaining member 31. The substrate
retaining member 31 of the retaining plate 30 can retain and release a
wafer W just by vertically moving the lift pin plate 20 using a vertical
driving unit 50 (described later). The configuration of the substrate
cleaning apparatus 10 can thus be simplified. It also reduces the time
lag between the timing of raising and lowering of the lift pin plate 20
and the timing of the action of the substrate retaining member 31,
whereby improving throughput.

[0052] As shown in FIGS. 2A and 23, the treatment fluid supply pipe 40 is
arranged to pass through both the through-hole 20a in the lift pin plate
20 and the through-hole 30a in the retaining plate 30. The treatment
fluid supply pipe 40 is arranged such that it does not rotate when the
lift pin plate 20 and the retaining plate 30 rotate. Extending through
the treatment fluid supply pipe 40 in the axial direction thereof are: a
liquid supply passage 40a through which, as a cleaning liquid, a chemical
liquid such as DHF (dilute hydrofluoric acid) solution and SC1 (Standard
Clean 1) solution, and a rinse liquid such as DIW (deionized water)
flows; and a gas supply passage 40b through which a gas, such as an inert
gas, e.g., N2 gas flows. The bar-shaped nozzle 60 which will be
detailed later is attached to the upper end of the treatment fluid supply
pipe 40.

[0053] As shown in FIGS. 2A, 2B, and 9, the vertical driving unit 50 is
connected with the treatment fluid supply pipe 40 via a connecting member
52. The vertical driving unit 50 is configured to move the treatment
fluid supply pipe 40 vertically. That is, by raising/lowering the
connecting member 52, the vertical driving unit 50 moves the treatment
fluid supply pipe 40 and bar-shaped nozzle 60 connected to the connecting
member 52. More specifically, the vertical driving unit 50 raises/lowers
the treatment fluid supply pipe 40 and the bar-shaped nozzle 60 between
their lowered positions as in FIG. 2A and their raised positions as in
FIG. 2B.

[0054] As shown in FIG. 9, the treatment fluid supply pipe 40 is further
attached with a first interlocking member 44. Three rod-shaped second
interlocking members 46 are connected to the first interlocking member 44
to extend upward therefrom. The second interlocking members 46 are
arranged to correspond to the connecting members 24 extending downward
from the lift pin plate 20. The outer diameter of the second interlocking
member 46 is smaller than the inner diameter of the cylindrical
accommodation member 32. That is to say, each second interlocking member
46 is arranged to contact the bottom of one connecting member 24 so that
the second interlocking member 46 can push the connecting member 24
upward within the accommodation member 32, as shown in FIG. 2B.

[0055] Accordingly, when the vertical driving unit 50 moves the treatment
fluid supply pipe 40 upward from the state shown in FIG. 2A, the first
interlocking member 44 and second interlocking members 46 joined with the
treatment fluid supply pipe 40 also moves upward so that the second
interlocking members 46 push the connecting members 24 upward inside the
accommodation members 32, whereby the lift pin plate 20 moves integrally
with the treatment fluid supply pipe 40 so that the lift pin plate 20,
the treatment fluid supply pipe 40, and the bar-shaped nozzle 60 thus
reach their raised positions as in FIG. 2B. On the other hand, when the
vertical driving unit 50 moves the treatment fluid supply pipe downward
from the state shown in FIG. 2B, since the spring 26 set within the
accommodation member 32 constantly applies a downward force to the
connecting member 24, the connecting member 24 descends downward
integrally with the interlocking member 46 with its bottom being in
contact with the top of the second interlocking member 46. The lift pin
plate 20, the treatment fluid supply pipe 40, and the bar-shaped nozzle
60 thus reach their respective lowered positions as in FIG. 2A.

[0056] The lift pin plate 20 adjoins the retaining plate 30 when the lift
pin plate 20 is positioned at its lowered position, as shown in FIG. 2A.
In the illustrated embodiment, the lift pin plate 20 is rested on and
supported by the retaining plate 30. On the other hand, the lift pin
plate 20 is separated from the retaining plate 30 when the lift pin plate
20 is positioned at its raised position, as shown in FIG. 2B. The wafer W
is then supported by the lift pins 22 and can be removed therefrom.

[0057] As mentioned above, the liquid treatment apparatus includes an
interlocking mechanism having the first interlocking member 44 and the
three second interlocking members 46 for integrally raising and lowering
the lift pin plate 20, the treatment fluid supply pipe 40, and the
bar-shaped nozzle 60. The liquid treatment apparatus also includes a
lifting mechanism for integrally raising and lowering the lift pin plate
20, the treatment fluid supply pipe 40, and the bar-shaped nozzle 60
relative to the retaining plate 30 by employing the first interlocking
member 44, the three second interlocking members 46, the vertical driving
unit 50 and the connecting member 52.

[0058] Next, the configuration of the bar-shaped nozzle 60 will be
described below with reference to FIGS. 2A, 2B, 9, and 10. The bar-shaped
nozzle 60 includes a bar-shaped portion 60A and a central portion 60B.
The bar-shaped nozzle 60 is attached via the central portion 60B to the
upper end of the treatment fluid supply pipe 40. The central portion 60B
also serves as a covering member for covering the through-hole 20a in the
lift pin plate 20. The bar-shaped portion 60A extends from the central
portion 60B in a radially outward direction of the lift pin plate 20,
that is, a radially outward direction of the wafer W, and terminates
slightly before an imaginary circle along which the lift pins 22 are
arranged so as not to interfere with the pins 22.

[0059] As shown in FIG. 10, the bar-shaped portion 60A has a cross section
like an airfoil. In this liquid treatment apparatus, the wafer W rotates
in a direction of the arrow R shown in FIG. 10(b) with respect to the
bar-shaped portion 60A. The rotation of the wafer W generates an
airstream flowing in the direction of the arrow R in the space between
the lower surface of the wafer W and the lift pin plate 20. This
airstream passing through the space above the bar-shaped portion 60A
improves the flow of the liquid. More specifically, as the airstream
passes through a space between the back side of the bar-shaped portion
60A and the wafer W, the airstream will be accelerated by the throttle
effect and deflected in a direction towards the lower surface of the
wafer W. Such airstream assists the treatment liquid (e.g., a chemical
liquid) that has collided with the lower surface of the wafer W to spread
more smoothly over the lower surface. In addition, since the bar-shaped
portion 60A has a cross section like an airfoil, vibration of the
bar-shaped portion 60A due to the airstream can be suppressed to a
minimum.

[0060] The upper surface of the bar-shaped portion 60A is provided with a
plurality of ejection ports 61 (first ejection ports) arranged in the
longitudinal direction of the bar-shaped portion 60A. Their arrangement
pitch may be between about 1 and 2 mm, and the hole diameter may be
between about 0.2 and 0.5 mm. The central portion 60B is also provided
with a plurality of ejection ports 62 (second ejection ports).

[0061] The treatment fluid supply pipe 40 has, at its upper end, a head 41
of an enlarged diameter. The central portion 60B of the bar-shaped nozzle
60 includes hollow engaging protrusions 63a and 63b on a lower surface of
the central portion 60B. The liquid supply passage 40a and the gas supply
passage 40b extending through the treatment fluid supply pipe 40 are
opened at the upper surface of the head 41, into which the engaging
protrusions 63e and 63b are fitted, respectively. A truncated conical
cover 65 is attached to the lower surface of the central portion 60B to
provide the central portion 60B with a function of a covering member for
covering the through-hole 20a in the lift pin plate 20. The rim of the
cover 65 is located above the circular protrusion 20b (see FIGS. 2A and
3) formed around the through-hole 20a in the lift pin plate 20. In this
embodiment, the cover 65 is integrated with the central portion 60B of
the bar-shaped nozzle 60 by jointing the head 41 of the treatment fluid
supply pipe 40 and the central portion 60B together via bolts 64, with
the cover 65 interposed between the central portion 60B and the head 41
of the treatment fluid supply pipe 40. The cover 65 may instead be
initially formed integrally with the central portion 60B. Although the
cover 55 is preferred to have a truncated conical shape, the shape of the
cover 65 is not limited to that as illustrated, and any shape is possible
as long as it covers the through-hole 20a and prevents liquid entering.
Further, the cover 65 may be formed integrally with the head 41 of the
treatment fluid supply pipe 40. The head 41 attached with the cover can
be jointed with the central portion 608 to give the central portion 60B
the function of a covering member.

[0062] The central portion 60B of the bar-shaped nozzle 60A houses a
liquid passageway 66a and a gas passageway 66b which respectively
communicates with the liquid supply passage 40a and the gas supply
passage 40b. The liquid passageway 66a and the gas passageway 66b extend
radially outward to the distal end portion of the bar-shaped portion 60A
of the bar-shaped nozzle 60 (along the longitudinal direction of the
bar-shaped nozzle 60), horizontally and in parallel to each other.

[0063] As shown in FIG. 10(b), each ejection port 61 on the bar-shaped
portion 60A is connected to a liquid ejecting passage 67a and a gas
ejecting passage 67b. The liquid ejecting passage 67a and the gas
ejecting passage 67b are respectively connected with the liquid
passageway 56a and the gas passageway 66b. The liquid ejecting passage
67a and the gas ejecting passage 67b meet at the upper surface or near
the upper surface of the bar-shaped portion 60A (i.e., at the ejection
port 61 or at its vicinity).

[0064] As shown in FIG. 10(c), each ejection port 62 on the central
portion 60B is connected to a liquid-ejecting passage 68a and a
gas-ejecting passage 68b. The liquid-ejecting passage 68a and the
gas-ejecting passage 68b is respectively connected with the liquid
passageway 66a and the gas passageway 66b. The liquid ejecting passage
68a and the gas ejecting passage 68b meet below the upper surface of the
central portion 60B and the combined passage is lead to the ejection port
62. The aperture diameter of the ejection port 62 is larger than that of
the ejection port 61.

[0065] Referring to FIG. 2A, the liquid supply passage 40a and gas supply
passage 40b in the treatment fluid supply pipe 40 are respectively
connected to a liquid supply mechanism 70 and a gas supply mechanism 80.
The liquid supply mechanism 70 includes a first liquid supply unit 70a
for supplying at least one kind of chemical liquid (one liquid in this
embodiment) to the liquid supply passage 40a, and a second liquid supply
unit 70b for supplying DIW (deionized water) as a rinsing liquid to the
liquid supply passage 40a. The first liquid supply unit 70a is connected
to a chemical liquid supply source (CHM) 71a containing DHF or SC1, etc.
via a line 74a. The line 74a comprises, from the upstream side, a
variable throttle valve 72a and an open/close valve 73a. Similarly, the
second liquid supply unit 70b is connected to a DIW supply source 71b via
a line 74b, and the line 74b is provided with a variable throttle valve
72b and an open/close valve 73b from the upstream side. The lines 74a and
74b meet at a downstream of the open/close valves 73a and 73b, and then
connected to the liquid supply passage 40a. Open/close valves denoted by
reference numbers 75 and 76 are used to drain liquids remained in the
lines 74a and 74b. If it is necessary to supply two or more kinds of
chemical liquids to the liquid supply passage 40a, for example, if SC1
cleaning and DHF cleaning is to be executed successively, an additional
liquid supply unit having a similar configuration as that of the first
liquid supply unit 70a may be provided in parallel.

[0066] The gas supply mechanism 80 is provided to supply gas such as an
inert gas (in the illustrated embodiment, N2 gas) to the gas supply
passage 40b. The gas supply mechanism 80 and an N2 gas supply source
81 is connected to with a line 84a, and the line 84a is provided from the
upstream side with a variable throttle valve 82 and an open/close valve
83.

[0067] The substrate cleaning apparatus 10 further includes a
configuration for supplying treatment fluid to the upper surface of the
wafer W retained by the retaining plate 30. In the illustrated
embodiment, the substrate cleaning apparatus 10 has a chemical liquid
supply nozzle 91 for ejecting chemical liquid to the upper surface of the
wafer W; a two-fluid nozzle 92 for Jetting a mist of a fluid mixture
including DIW and N2 gas to the upper surface of the wafer W. The
chemical liquid supply nozzle 91 and the two-fluid nozzle 92 can be moved
by a nozzle driving mechanism 93 from the center of the wafer W to its
peripheral edge. In other words, the nozzles can supply the treatment
fluid while scanning the upper surface of the wafer W. The nozzle driving
mechanism 93 can also move the chemical liquid supply nozzle 91 and the
two-fluid nozzle 92 to a standby position (not shown) outside the outer
cup 56. The chemical liquid supply source 71a can feed chemical liquid to
the chemical liquid supply nozzle 91 at a controlled flow rate through a
variable throttle valve 94a and an open/close valve 95a. Similarly, the
DIW supply source 71b and the N2 gas supply source 81 can feed DIW
and N2 gas to the two-fluid nozzle 92 at controlled flow rates by
through variable throttle valves 94b, 94c and open/close valves 95b, 95c.
The nozzle driving mechanism 93 may be a type that uses a pivotal arm
holding a nozzle(s) at its distal end, or a type that uses an arm guided
by a guide rail for translational motion and holding a nozzle(s) at its
distal end. Further, a single nozzle driving mechanism (93) may drive
both the chemical liquid supply nozzle 91 and the two-fluid nozzle 92, or
alternatively, the chemical liquid supply nozzle 91 and the two-fluid
nozzle 92 may each have an independent nozzle-driving mechanism.

[0068] The substrate cleaning apparatus 10 includes a controller 100 that
controls the whole operation of the apparatus. The controller 100
controls operation of all functional components of the substrate cleaning
apparatus 10 (e.g., the rotational driving unit 39, the vertical driving
unit 50, the open/close valves, the variable throttle valves, the nozzle
driving mechanism 93, etc.). The controller 100 can be implemented with
hardware such as a general-purpose computer, and a program as software
for controlling the computer (apparatus control program, processing
recipe, etc.). The software may be stored in a hard-disk drive or other
storage medium fixedly provided in the computer, or may be stored in a
storage medium removably set in the computer such as a CD-ROM, DVD, flash
memory. Such a storage medium is denoted with reference number 106. Upon
receipt of instructions from a user interface (not shown), a processor
107 calls up a required processing recipe from the storage medium 106 and
executes the recipe. The controller 100 thereby controls and operates the
functional components of the substrate cleaning apparatus 10 to perform a
predetermined process (treatment). Alternatively, the controller 100 may
be a system controller that controls the whole operations of the liquid
treatment system shown in FIG. 1.

[0069] Next, the manner of ejecting treatment fluids (processing fluids)
from the bar-shaped nozzle 50 is described. There are two ejection modes
set for the bar-shaped nozzle 60 to eject the treatment fluid.

[0070] (First Ejection Mode)

[0071] In a first ejection mode, a chemical liquid such as DHF is fed to
the liquid supply passage 40a of the treatment fluid supply pipe 40 while
no gas is fed to the gas supply passage 40b. As shown in FIG. 11(b), the
chemical liquid is fed to the bar-shaped portion 60A through the liquid
passageway 66a and the liquid ejecting passage 62a, and then ejected
toward the lower surface of the wafer W from the ejection ports 61. The
liquid-ejecting passage 57a is inclined to the rotating direction of the
wafer W, and the ejection port 61 is formed so as not to change the
direction of liquid flow in the liquid ejecting passage 67a. Therefore,
the chemical liquid is ejected obliquely from the ejection port 61. The
vector representing the ejecting direction of the chemical liquid has a
component of the rotating direction of the wafer W. By ejecting the
chemical liquid to the wafer W in such a manner, bouncing (splash-back)
of the chemical liquid upon collision against the lower surface of the
wafer W can be suppressed. This reduces waste of the treatment liquid and
increases efficiency of treatment liquid usage.

[0072] The plurality of ellipses in FIG. 12 each represent an area where
an ejected liquid covers on the lower surface of the wafer W at the
instant of reaching the surface (this area is hereinafter also referred
to as "spot"). After reaching the lower surface of the wafer W, the
chemical liquid ejected from the ejection port 61 spreads on the surface
due to factors such as a centrifugal force of the rotation of the wafer
W, and the pressure of ejecting from the ejection port 61. In a plan
view, each ejection port 61 in the bar-shaped portion 60A ejects the
liquid in a tangential direction of a circle that passes through the
particular ejection port 61 and has its center at the wafer center. Thus,
a pitch P between the centers of the elliptical spots is equal to the
arrangement pitch of the ejection ports 61. Since the liquid diffuses
after being ejected, a minor axis of each ellipse has a length "B" that
is greater than a diameter of the ejection port 61. A major axis of the
ellipse has a length "A" much greater than the diameter of the ejection
port 61 because the liquid is ejected from the ejection port 61 at an
angle inclined to the direction of the wafer rotation. Adjacent
elliptical spots form an overlapped area with a certain length L.

[0073] The ejection port 62 of the central portion 60B in the first
ejection mode is configured to turn the flow of the chemical liquid from
the liquid ejecting passage 67a into a vertically upward direction. The
chemical liquid is ejected vertically upward from the ejection port 62.
The chemical liquid thus forms a circular spot on the lower surface of
the wafer W. The reason for ejecting the chemical liquid vertically
upward is that the part of the wafer W above the central portion 50B has
a low circumferential velocity and it is thus not so advantageous to
eject the chemical liquid obliquely. Additionally, oblique ejecting of
the chemical liquid may rather reduce uniformity of the treatment near
the wafer center.

[0074] FIG. 11(a) shows the spots formed by the chemical liquid ejected
from the ejection ports 61, 62 onto the lower surface of the wafer W at
the instant of reaching the lower surface. The small white circles denote
the ejection ports 61, "x" marks denote the centers of the ejection ports
62, the white ellipses denote the spots formed by the chemical liquid
ejected from the ejection ports 61, and the larger white circles denote
the spots formed by the liquid ejected from the ejection ports 62.

[0075] At least some (in the illustrated embodiment, five) of the ejection
ports 61 positioning at the distal end portion on the bar-shaped portion
60A are oriented in a direction shifted radially outward (see arrow D2)
from the tangential direction (arrow D1) at an angle θ, in a plan
view. These distal ejection ports 61 form flows of chemical liquid
flowing towards outside of the wafer W, whereby unnecessary substances
and contaminants having been removed from the lower surface of the wafer
W are flushed out of the wafer W. As an example of such configuration,
the most distal ejection port 61 may have the maximum angle, and an angle
θ of the ejection ports 61 may decrease as it approaches the
proximal end. An ejection port 61 at a certain position counted from the
outermost port 61, in this case the sixth one, can be adapted to have an
angle θ of 0 degrees. If the angles θ are not zero, the
overlapping length L between the adjacent elliptical spots are smaller.

[0076] Depending on the kind of treatment, the overlapping length (radial
length) L between the adjacent elliptical spots may possibly affect
in-plane uniformity of the surface being treated. In a case where such
problem is expected, it is preferable to change the ejecting pressure
(force) of the chemical liquid from the ejection port 61 by adjusting the
variable throttle valve 72a. If the ejecting pressure (force) of the
chemical liquid is sufficiently high, the liquid spreads out in a burst
immediately after reaching the lower surface of the wafer W (at the
instant of liquid reaching the surface, the size of spots is not
different so much depending on the ejecting pressure). The size of
elliptical spots thus substantially increases, thereby to produce the
same effect as that obtained by increasing the overlapping length L. The
ejecting (discharging) pressure of the liquid can be changed in a
pulse-like manner as by alternating high and low pressure, or may be
changed continuously in accordance with a predetermined control curve
such as a sine curve.

[0077] Alternatively or in addition to the above, the chemical liquid may
be ejected from the ejection port 61 while moving the bar-shaped nozzle
60. The bar-shaped nozzle 50 may be moved by using a horizontal moving
mechanism 54 mounted at the bottom of the vertical driving unit 50
(schematically depicted with a dashed line in FIG. 9). A function similar
or equivalent to that of the horizontal moving mechanism 54 can be
incorporated in the connecting member 52 as an alternative method. The
horizontal moving mechanism 54 slightly shifts the treatment fluid supply
pipe 40 in the horizontal direction to move the bar-shaped nozzle 60 in
the longitudinal direction of the bar-shaped portion 60A. As the position
of the overlapped areas between the adjacent elliptical spots changes,
uniformity of the treatment can be improved. The moving distance of the
bar-shaped nozzle 60 may be the same as or less than the arrangement
pitch of the ejection ports 61 on the bar-shaped nozzle 60. The
horizontal moving mechanism 54 can be constructed with a ball screw
driven by an electric motor for example. Any other mechanism can be
adopted as long as it is suitable of linear driving for a slight amount.

[0078] Referring to FIG. 11(a), as can be seen from arc C depicted with
dashed lines, the spot formed by the chemical liquid that has been
ejected from the ejection port 62 closest to the bar-shaped portion 60A,
and the spot formed by the chemical liquid that has been ejected from the
ejection port 61 closest to the central portion 60B, form an overlapped
area. The length of this overlapped area can also be changed by
controlling the ejecting pressure of the chemical liquid.

[0079] The ejection ports 61 do not need to be strictly arranged on a
radius of the wafer (i.e., on a straight line passing through the center
of the wafer) as long as the spots formed by the chemical liquid ejected
from the ejection ports 61 are generally aligned in a radial direction of
the wafer. In the configuration shown in FIG. 11(a), only the ejection
ports 62 are exactly positioned in the radial direction of the wafer
(i.e., on the straight line passing through the center of the wafer);
while the ejection ports 61 are arranged on a straight line parallel to
and slightly shifted from the line passing the wafer center.
Alternatively, all of the ejection ports 61, 52 may be arranged on one
straight line in a plan view, for example, on a straight line passing
through the wafer center (see FIG. 16(a)). In another embodiment, all
spots formed by the chemical liquid ejected from the ejection ports 61,
62 may be arranged on one straight line, for example, on a straight line
passing through the wafer center (see FIG. 16(b)). The spots formed by
the chemical liquid ejected from the ejection ports 61, 62 may form a
broken line (see FIG. 16(c)). The arrangement line on which the ejection
ports 61 are arrayed may be curved to some degree. Anyway, it is
sufficient if the plurality of ejection ports 61 are arrayed in an area
extending from a position opposing the central portion of the wafer W
(substrate) to a position opposing the peripheral portion of the wafer.

[0080] (Second Ejection Mode)

[0081] In a second ejection mode, DIW is fed to the liquid supply passage
40a in the treatment fluid supply pipe 40, and N2 gas is fed to the
gas supply passage 40b. At the bar-shaped portion 60A, as shown in FIG.
13(a), DIW is guided to each ejection port 61 via the liquid passageway
66a and the liquid ejecting passage 57. Similarly, N2 gas is guided
to each ejection port 61 via the gas passageway 66b and the gas ejecting
passage 67b. The DIW and the N2 gas collide at the ejection port 61
to form a mist of a fluid mixture including the DIW and the N2 gas,
that is, a two-fluid spray. Due to the collision between the DIW and the
N2 gas, the two-fluid spray blows upward while spreading in a
fan-like fashion. The collision energy of the two-fluid spray cleans the
lower surface of the wafer W. In this case, the vector representing the
ejecting direction (principal direction) of the two-fluid spray is
directed vertically upward. The vector substantially does not have a
component of the rotational direction of the wafer W. This is preferable
in this mode since the cleaning effect of the two-fluid spray relies on
the collision energy or the two-fluid spray. It is also preferable if the
vector representing the ejecting direction (principal direction) of the
two-fluid spray has a component of the direction opposite to the
direction of the wafer W rotation.

[0082] In the second ejection mode, since the ejection port 62 of the
central portion 60B is formed to turn the flows of the DIW and the
N2 gas supplied from the liquid ejecting passage 68a and the gas
ejecting passage 68b vertically upward, the two-fluid spray ejected from
the ejection port 62 moves upward while spreading in a fan-like fashion.

[0083] As with the first ejection mode, the two-fluid spray may be ejected
onto upon the lower surface of the wafer W while changing both or one of
the DIW ejecting pressure and the N2 gas ejecting pressure by
adjusting the opening of the variable throttle valves 72b, 82.

[0084] Next, a series of process steps executed by the substrate cleaning
apparatus 10 will be described below.

[0085] First, the lifting mechanism moves the lift pin plate 20, the
treatment fluid supply pipe 40, and the bar-shaped nozzle 60, to their
respective raised positions shown in FIG. 2B. Next, as shown by
double-dashed lines in FIG. 2B, a wafer W is carried into the cleaning
apparatus 10 from outside by the transport arm 104. The wafer W is placed
on the lift pins 22 of the lift pin plate 20.

[0086] The vertical driving unit 50 next moves the treatment fluid supply
pipe 40 and the bar-shaped nozzle 60 from their raised positions to their
lowered positions. At this time, since the spring 26 housed in the
accommodation member 32 constantly applies a downward force to the
connecting member 24, the lift pin plate 20 also moves downward with the
treatment fluid supply pipe 40 to the downward movement position. The
lower surface of the lift pin plate 20 then pushes the pressure receiving
member 31c of the substrate retaining member 31 downward from the state
shown in FIG. 6. The substrate retaining member 31 rotates around the
axle 31a in the counterclockwise direction in FIG. 6. The substrate
retaining portion 31b of the substrate retaining member 31 thus moves
towards the wafer W from the lateral side of the wafer (see FIG. 7), and
the substrate retaining member 31 thus retains the wafer W from its
lateral side (see FIG. 8). At the point of time when the wafer W is just
retained from its lateral side by the substrate retaining member 31, the
wafer W is lifted to be separated upward from the lift pin 22. Normally,
the wafer W is retained by the retaining plate 30 in such a manner that
its "front surface" (the surface on which devices are to be formed) comes
to the "upper surface" and its "back surface" comes to the "lower
surface" (the surface on which no devices are to be formed). In this
disclosure, the term "upper surface" (or "lower surface") simply means a
face that is facing upward (downward) at a particular point of time.

[0087] After the lift pin plate 20, the treatment fluid supply pipe 40,
and the bar-shaped nozzle 60 have reached their respective lowered
positions shown in FIG. 2A, the nozzle driving mechanism 93 is activated
to move the chemical liquid supply nozzle 91 to a position above the
center of the upper surface of the wafer W. Next, the rotational driving
unit 39 is activated to rotate the retaining plate 30. At this time,
since the connecting members 24 extending downward from the lower surface
of the lift pin plate 20 is inserted within the accommodation members 32
extending downward from the lower surface of the retaining plate 30, the
lift pin plate 20 rotates interlockingly with the rotation of the
retaining plate 30, whereby rotating the wafer W as well. The treatment
fluid supply pipe 40 and the bar-shaped nozzle 60 connected thereto
remain still and does not rotate during the rotation.

[0088] Next, the chemical liquid supply nozzle 91 located above the wafer
center starts supplying the chemical liquid such as DHF to the upper
surface of the wafer W with the wafer W being rotated. While the chemical
liquid is supplied to the upper surface of the wafer W, the nozzle
driving mechanism 93 moves the chemical liquid supply nozzle 91 radially
outward over the wafer W until the nozzle 91 reaches the wafer edge. The
upper surface of the wafer W is thus cleaned with the chemical liquid by
the so-called scanning method.

[0089] Simultaneously with the start of cleaning the upper surface of the
wafer W with the chemical liquid, the bar-shaped nozzle 60 supplies a
chemical liquid (the same chemical liquid as that supplied to the upper
surface of the wafer W) onto the lower surface of the rotating wafer W in
the first ejection mode, whereby the lower surface of the wafer W is
subjected to chemical cleaning.

[0090] After the chemical liquid cleaning, a liquid droplet treatment
(process) using a liquid-gas fluid mixture is conducted to remove
particles. The two-fluid nozzle 92 is moved to a position above the
center of the upper surface of the wafer W by the nozzle driving
mechanism 93, and the wafer W starts rotating. The two-fluid nozzle 92
supplies the upper surface with a two-fluid spray which is the fluid
mixture of DIW and N2 gas while being moved radially outward to the
wafer edge by the nozzle driving mechanism 93. Thus, the liquid droplet
treatment of the upper surface of the wafer W is performed in the
so-called scanning method.

[0091] Simultaneously with the start of the liquid droplet treatment of
the upper surface of the wafer W, the bar-shaped nozzle 60 ejects or jets
a two-fluid spray which is the fluid mixture of DIW and N2 gas to
the lower surface of the rotating wafer W in the second ejection mode.
The lower surface of the wafer W is thus also subjected to liquid droplet
treatment. Since the liquid droplet treatment provides a strong physical
cleaning effect, the chemical liquid used in the preceding treatment and
particles can be removed efficiently.

[0092] After the liquid droplet treatment, the wafer W is rotated for
drying.

[0093] When the successive processes are all completed, the vertical
driving unit 50 moves the treatment fluid supply pipe 40 and the
bar-shaped nozzle 60 from their lowered positions to raised positions.
The second interlocking members 46 push the connecting members 24 to
raise the lift pin plate 20 from its lowered position to its raised
position interlockingly with the raising of the treatment fluid supply
pipe 40. At the same time, the biasing force of the spring 26 rotates the
substrate retaining member 31 around the axle 31a in the counterclockwise
direction in FIG. 6 (i.e., in a direction opposite to the arrow in FIG.
6). The substrate retaining portion 31b leaves from the side of the wafer
W and the lower surface of the wafer W is then supported by the lift pins
22.

[0094] After the lift pin plate 20, the treatment fluid supply pipe 40,
and the bar-shaped nozzle 60 have reached their respective raised
positions as shown in FIG. 2B, the wafer W rested on the lift pins 22 is
removed from the lift pins 22 by the transport arm 104. The wafer W,
after being removed by the transport arm 104, is carried to the outside
of the substrate cleaning apparatus 10.

[0095] In the foregoing embodiment, due to the use of the nozzle having
the plurality of ejection ports 61 arrayed along a line connecting a
position opposing the central portion of the wafer W and a position
opposing the peripheral portion of the wafer W, the lower surface of the
wafer W can be treated with high in-plane uniformity. The amount of
consumption of treatment fluid(s) can be reduced. The lower surface of
the wafer W can be washed or flushed uniformly. Additionally, the
direction in which the liquid is ejected from the ejection ports 61 is
inclined in the rotational direction of the wafer W, in other words, the
ejection ports 61 are formed such that the direction in which the
treatment liquid is ejected has a component of the rotating direction of
the wafer W. This suppresses splashing of the treatment liquid upon its
collision with the lower surface of the wafer W and reduces waste
thereof. Further, generation of particles due to re-adhesion of the
splashed liquid can be suppressed. Since the ejection ports in the distal
end portion of the nozzle is directed outward, the treatment liquid
supplied onto the wafer surface can be flushed out of the wafer surface.

[0096] Further, in the Foregoing embodiment, the lower surface of the
wafer W can be treated concurrently with the upper surface of the wafer
W, with a high in-plane uniformity substantially equivalent to that of
the treatment of the upper surface. Thus, throughput can be improved
while achieving a treatment result of high quality.

[0097] The lift pin plate 20, the treatment fluid supply pipe 40, and the
bar-shaped nozzle 60 move vertically relative to the retaining plate 30,
and the lift pins 22 for supporting the lower surface of the wafer W are
provided on the lift pin plate 20. In addition, the cover 65 is provided
between the treatment fluid supply pipe 40 and the bar-shaped nozzle 60
to cover the through-hole 20a in the lift pin plate 20. Since the cover
65 covers the through-hole 20a of the lift pin plate 20, the cleaning
liquid is prevented from entering the through-hole 20a for inserting the
treatment fluid supply pipe 40. Further, in the foregoing embodiment, the
lift pins 22 are provided on the lift pin plate 20. As compared with a
conventional apparatus having lift pins to be retracted into
through-holes formed in a bottom plate, the apparatus in the foregoing
embodiment is advantageous in that there will be less cleaning liquid
left on the lift pins 22 after drying a wafer W, which prevents the
cleaning liquid from re-adhering to the lower surface of the wafer W
after cleaning. This is because the lift pins 22 rotate integrally with
the lift pin plate 20. Since the lift pins 22 rotates integrally with the
lift pin plate 20, adhesion of droplets of the cleaning liquid onto the
lift pins 22 can be suppressed, whereby the re-adhering of the cleaning
liquid to the lower surface of the cleaned wafer W can be prevented more
effectively.

[0098] In the foregoing embodiment, since the treatment fluid supply pipe
40 and the bar-shaped nozzle 50 move vertically together with the lift
pin plate 20, the cover 65 covers the through-hole 20a of the lift pin
plate 20 also during vertical movement of the treatment fluid supply pipe
40 and the lift pin plate 20, and the cleaning liquid is prevented from
entering the through-hole 20a more effectively.

[0099] Since the rotary cup 36 is provided on the retaining plate 30, the
cleaning liquid is prevented from scattering externally from the rotating
wafer W during cleaning. Further, due to the substrate retaining member
31 attached on the retaining plate 30, the wafer W can be stably retained
during rotation by supporting the wafer W from its lateral side.

[0100] The foregoing description of the embodiment describes a case where
the ejection ports 61 inject fluid such as a chemical liquid or DIW while
changing the position of the bar-shaped nozzle 60 by the horizontal
moving mechanism 54. This case is further describes in detail below
referring to FIG. 17.

[0101] First, the reason for shifting the lateral position of the
bar-shaped nozzle 60 while ejecting the treatment liquids from the
ejection ports 61 will be described. It is assumed that a treatment
liquid is supplied from the chemical liquid supply source 71a or the DIW
supply source 71b to the bar-shaped nozzle 60 at a constant (fixed)
pressure. In such a case, as the number of ejection ports 61 increases
and/or the hole diameter of the ejection ports 61 increases, the velocity
of the treatment liquid ejected from each ejection port 61 decreases.
Under the condition that the feed pressures of the chemical liquid supply
source 71a and the DIW supply source are fixed, the number of ejection
ports 61 and their hole diameter each need to be limited in order to
maintain the velocity of the liquid ejected (jetted) from each ejection
port 61 at a predetermined desired value. When the number of ejection
ports 61 and their hole diameter each are limited as above, two adjacent
spots formed on the lower surface of the wafer W by the treatment liquid
concurrently ejected from two adjacent ejection ports 61 may not overlap
with each other, in a plan view. In such case, it is advantageous to
shift the lateral position of the bar-shaped nozzle 60 during the
ejection of the treatment liquid from the ejection ports 61.

[0102] FIG. 17 shows schematic plan views showing states of when the
liquid is ejected from the ejection ports 61 while shifting the position
of the bar-shaped nozzle 60. As shown in FIG. 17(a), at least some of the
plurality of ejection ports 61 are arranged at a predetermined pitch P
along the horizontal line on which the plurality of ejection ports 61
lay. The arrow L in FIG. 17(a) denotes a direction in which the
horizontal line connecting the arranged ejection ports 61 extends
(hereinafter, this direction is referred to as the arrangement direction
L), FIG. 17(b) is a schematic plan view that shows a state in which the
position of the bar-shaped nozzle 60 is shifted through one third (1/3)
of the arrangement pitch P in the arrangement direction L, from the
position in FIG. 17(a) towards the peripheral edge of the wafer W. FIG.
17(c) is a schematic plan view that shows a state in which the position
of the bar-shaped nozzle 60 is shifted by one third of the arrangement
pitch P in the arrangement direction L, from the position in FIG. 17(b)
towards the peripheral edge of the wafer W.

[0103] First, the ejection ports 61 eject a treatment liquid (processing
liquid) to the lower surface of the wafer W in the first ejection mode
with the bar-shaped nozzle 60 placed at a predetermined position (first
position). FIG. 17(a) shows a spot S1 formed on the lower surface of the
wafer W by the treatment liquid ejected from each ejection port 61 at the
moment the treatment liquid reaches the lower surface of the wafer W. In
FIG. 17(a), the spot S1 is depicted as an elliptical region surrounded by
a solid line. The ejection of the treatment liquid from the bar-shaped
nozzle 60 in the first position is continued for a time period
corresponding to at least one revolution (360 degrees) of the wafer W.

[0104] Next, as shown in FIG. 17B, the horizontal moving mechanism 54
shifts the bar-shaped nozzle 60 through one third of the arrangement
pitch P, in the arrangement direction L towards the edge of the wafer W.
Then at this position (second position), each ejection port 61 ejects
treatment liquid to the lower surface of the wafer W in the first
ejection mode. In FIG. 17(b), depicted by a solid line is a spot S2,
which is formed on the lower surface of the wafer W by the treatment
liquid ejected from each ejection port 61 at the moment the treatment
liquid reaches the lower surface of the wafer W, when the bar-shaped
nozzle 60 is positioned at the second position. In FIG. 17(b), the spot
S1 formed when the bar-shaped nozzle 60 is in the first position is
depicted by dotted lines. The second position is set such that one spot
S1 formed when the bar-shaped nozzle 60 is in the first position and one
spot S2 formed when the bar-shaped nozzle 60 is in the second position
partially overlap in a plan view. The ejection of the treatment liquid
from the bar-shaped nozzle 60 in the second position is continued for a
time period corresponding to at least one revolution (360 degrees) of the
wafer W.

[0105] Next, as shown in FIG. 17(c), the position of the bar-shaped nozzle
60 is further shifted by the horizontal moving mechanism 54 through one
third of the arrangement pitch P, towards the edge of the wafer W in the
arrangement direction L. Then at this position (third position), the
treatment liquid is ejected from each ejection port 61 to the lower
surface of the wafer W in the first ejection mode. In FIG. 17(c),
depicted by a solid line is a spot S3, which is formed on the lower
surface of the wafer W by the treatment liquid ejected from each ejection
port 61 at the moment the treatment liquid reaches the lower surface of
the wafer W, when the bar-shaped nozzle 60 is positioned at the third
position. In FIG. 17(c), the spot S1 and S2 formed when the bar-shaped
nozzle 60 is in the first and second positions are depicted by dotted
lines. The third position is set such that, in a plan view, one spot S3
partially overlaps with both one spot S1 and one spot S2 that were
respectively formed in the first and second positions of the bar-shaped
nozzle 60. This allows the lower surface of the wafer W to be fully
covered with the treatment liquid without any gaps in the arrangement
direction L of the ejection ports 61. The ejection of the treatment
liquid from the bar-shaped nozzle 60 in the third position is continued
for a time period corresponding to at least one revolution (360 degrees)
of the wafer W.

[0106] With the embodiment shown in FIG. 17, the treatment liquid can be
ejected from each ejection port 61 while changing the position of the
bar-shaped nozzle 60 in the arrangement direction L of the ejection ports
61. Accordingly, even if the hole diameter of each ejection port 61 is
small relative to the arrangement pitch P and thus the spots S1 formed on
the lower surface of the wafer W by the treatment liquid concurrently
ejected from any two adjacent ejection ports 61 cannot overlap with each
other in a plan view as in FIG. 17(a), the treatment liquid can be
supplied onto the lower surface of the wafer W without discontinuity in
the arrangement direction L of the ejection ports 61. Even if the
treatment liquid supplied from the chemical liquid supply source 71a or
the DIW supply source 71b to the bar-shaped nozzle 60 has a fixed
pressure, the number of ejection ports 61, the hole diameter of each
ejection port 61, and other parameters can be set freely while ensuring
the desired jetting (ejecting) velocity of the treatment liquid. In
addition, the treatment liquid can be uniformly supplied to the lower
surface of the wafer W by shifting the bar-shaped nozzle 60 during
ejection. In other words, uniform liquid treatment can be performed to
the lower surface of the wafer W.

[0107] In the embodiment shown in FIGS. 17, the position of the bar-shaped
nozzle 60 were shifted through one third of the arrangement pitch P in
the arrangement direction L. However, not limited thereto, the position
of the bar-shaped nozzle 60 may be shifted through half (1/2) of the
arrangement pitch P in the arrangement direction L, or one fourth (1/4)
of the arrangement pitch P in the arrangement direction L, or even finer.
The amount of the shift of the bar-shaped nozzle 60 per one shifting
operation may be set to an appropriate value in view of the arrangement
pitch P of the ejection ports 61 and the size of the spots S formed on
the wafer W by the treatment liquid ejected from the ejection ports 61.

[0108] In the embodiment shown In FIG. 17, the bar-shaped nozzle 60 was
intermittently moved from the first position, to the second position, and
to the third position. Alternatively, the treatment liquid may be ejected
from the ejection ports 61 while continuously moving the bar-shaped
nozzle 50 through a predetermined distance shorter than the arrangement
pitch P in the arrangement direction L. Uniform liquid treatment can also
be performed to the lower surface of the wafer W in this way. The moving
speed of the bar-shaped nozzle may be set to an appropriate value which
enables the treatment liquid to be continuously supplied onto the lower
surface of the wafer W without discontinuity in the arrangement direction
L of the ejection ports 61, in view of the size of the spots S and the
rotating speed of the wafer W.

[0109] In the embodiment shown in FIG. 17, the bar-shaped nozzle 60 moves
towards the edge of the wafer W in the arrangement direction L.
Alternatively, the bar-shaped nozzle 60 may be moved towards the center
of the wafer W in the arrangement direction L. Further, the bar-shaped
nozzle 60 may reciprocate in the arrangement direction L.

[0110] Such moving of the bar-shaped nozzle 60 may be Implemented in any
ways by the horizontal moving mechanism 54. For example, the controller
100 may control the horizontal moving mechanism 54 to implement the above
moving of the bar-shaped nozzle 60. In this case, a program for moving
the bar-shaped nozzle 60 in a predefined sequence is stored within the
storage medium 106 of the controller 100.

[0111] In one embodiment, all the plurality of ejection ports 61, rather
than some of them, may be arranged in the arrangement direction L at an
equal arrangement pitch P (i.e., regular intervals). The ejection ports
61 arranged at the equal pitch P as such may be formed even in a region
allowing the treatment liquid to be ejected onto the central portion of
the wafer W. Alternatively, the ejection ports 62 shown in FIGS. 10 (a),
(c) may be formed in a region allowing the treatment liquid to be ejected
onto the central portion of the wafer W, and the arrangement pitch of the
ejection port 62 may be equal to the arrangement pitch P of the ejection
ports 61. Such configuration also enables the treatment liquid to be
supplied uniformly to the entire lower surface of the wafer W.

[0112] The foregoing embodiments may be modified as follows.

[0113] In the forgoing embodiment, as shown in FIG. 14(a), the
liquid-ejecting passage 67a and the gas-ejecting passage 67b crossed
exactly at the opening of the ejection port 61 in the bar-shaped portion
60A. However, as shown in FIG. 14(b), the gas-ejecting passage 67b may
meet the liquid-ejecting passage 67a at a position slightly short of the
opening.

[0114] In the foregoing embodiment, the DHF cleaning (chemical liquid
treatment), the DIW rinsing, the liquid droplet treatment with DIW and
N2 gas, the DIW rinsing, and the spin drying are performed in that
order. However, the processes (treatments) performed by the substrate
processing apparatus in the foregoing embodiment is not limited to them.
For example, chemical liquid treatment (with DHF or any other appropriate
chemical liquid), DIW rinsing, and spin drying may be sequentially
performed. In this case, DIW rinsing may be performed by ejecting only
DIW without ejecting N2 gas. The chemical liquid treatment may be a
treatment that ejects a chemical liquid and N2 gas at the same time,
in other words, a so-called two-fluid chemical treatment that jets a
fluid mixture of the chemical liquid and N2 gas towards the wafer W.
The gas is not limited to N2 gas and may be any other appropriate
inert gas. Further alternatively, a reactive gas may be used depending on
the kind of liquid treatment.

[0115] The treatments performed by the substrate processing apparatus in
the foregoing embodiment may be various kinds of liquid treatments
performed to the back surface of a wafer in coating/developing processes:
For example, the treatment may be a cleaning process after development or
a removing process for an unnecessary resist film. Alternatively, the
treatment may be a process to the lower surface (e.g., back surface) of
the wafer to be performed as a pre-plating or post-plating process.

[0116] In the foregoing embodiment, as the substrate retaining unit of a
so-called spin chuck for retaining and rotating the wafer, an assembly
comprising the lift pin plate 20 and the retaining plate integrated with
the rotary cup 36 is used. However, the bar-shaped nozzle 60 in the
foregoing, embodiment may be combined with any of various types of spin
chucks to construct a liquid treatment apparatus, as long as the spin
chuck holds the peripheral edge of a wafer. For example, as shown
schematically in FIG. 15, a mechanical spin chuck 200 configured to hold
the peripheral edge of a wafer may be combined with the treatment fluid
supply pipe 40 and the bar-shaped nozzle 60 employed in the present
embodiment. The mechanical spin chuck 200 includes a rotating member 201,
a plurality of (three or four) wafer retaining members 203 mounted to the
rotating member 201, and a motor 202 for rotating the rotating member
201. The liquid treatment apparatus shown in FIG. 15 may be of a type
configured to exclusively treat only the lower surface of the wafer W,
unlike the foregoing embodiment. In this case, a nozzle for supplying the
treatment fluid to the upper surface is not necessary. Various
constituent elements can be added to the configuration shown in FIG. 15
(e.g., a cup for receiving splashes of the treatment fluid, a nozzle for
treating the upper surface, etc.). Incidentally, in an apparatus
employing a spin chuck as shown in FIG. 15, the distal end of the
bar-shaped nozzle 60 can be extended radially outward as far as possible,
as long as it does not interfere with the wafer retaining member 203.

[0117] In the foregoing embodiment, in the second mode, DIW guided through
the liquid-ejecting passage 67a and N2 gas guided through the
gas-ejecting passage 67b collide with each other at the ejection port 61
of the bar-shaped nozzle 60, whereby the DIW and the N2 gas form a
mist-like fluid mixture (two-fluid spray). In order to form such a
two-fluid spray, the bar-shaped nozzle 60 may be provided, in the inside
thereof, with a mixing section 69 in which the DIW and the N2 gas
collide with each other, as shown in FIG. 18(a). The mixing section 69 is
a space expanding as approaching the ejection port 61. More specifically,
the mixing section 69 is a truncated conical space with its base (the
face of a larger area) serving as the ejection port 61, and its top face
(the face of a smaller area) being positioned inside the bar-shaped
nozzle 60. The mixing section 69 provided inside the bar-shaped nozzle 60
shapes the two-fluid spray into a desirable shape, e.g., a shape of the
two-fluid spray spreading more isotropically. The lower surface of the
wafer W can then be cleaned more uniformly.

[0118] The gas-ejecting passage 67b that guides the N2 gas may be
configured to extend upward in the vertical direction as shown in FIG.
18(a). The two-fluid spray will thus be jetted in the vertical direction
which in turn renders the two-fluid spray to collide with the lower
surface of the wafer W in the vertical direction. Therefore, the
two-fluid spray can be collided with the lower surface of the wafer W
without reducing its energy. This allows the lower surface of the wafer W
to be cleaned efficiently.

[0119] In the embodiment of FIG. 18(a), the mixing section 69 and the
liquid-ejecting passage 67a are constructed in a manner that, in the
first ejection mode, a sidewall 69a defining the mixing section 69 does
not deflect liquid ejected from the ejection port 61 via the
liquid-ejecting passage 67a. More specifically, as shown in FIG. 18(b),
geometry parameters (e.g., angles t1 and c2, which are the angles with
respect to the vertical direction of the sidewall 69a and the
liquid-ejecting passage 67a; the hole diameters d1 and d2 of the ejection
port 61 and the liquid-ejecting passage 67a; and the position of
connection between the sidewall 69a and the liquid-ejecting passage 67a)
are determined such that a imaginarily extension of the liquid-ejecting
passage 67a towards the ejection port 61, that is, a space 67a' does not
contact the sidewalls 69a. The liquid guided through the liquid-ejecting
passage 67a is thus ejected obliquely from the ejection port 61 at the
angle φ2. The angle φ2 is preferably set so that the vector
representing the direction in which the treatment liquid is ejected from
the ejection port 61 has a component of the rotating direction R of the
wafer W.

[0120] In the foregoing embodiment, the liquid treatment apparatus is
configured such that the bar-shaped nozzle 50 can operate in two modes,
one being the first ejection mode for ejecting only a liquid, the other
being the second ejection mode for ejecting a two-fluid spray comprising
a mixed fluid of a liquid and a gas. However, if the ejection of the
two-fluid spray is not necessary, all the structural elements for
ejecting N2 gas (e.g., the gas supply passage 40b, the gas
passageway 66b, the gas ejecting passage 67b, 68b, the gas supply
mechanism 80, etc.) may be removed from the liquid treatment apparatus in
the foregoing embodiment.